Hey dude, I'll be honest, I wouldn't worry so much about the girl "problem". A lot of perfectly healthy people have that one and such things will eventually resolve themselves one way or the other. And if they don't, that's why beer exists :) And if beer doesn't work, then that's why tequila exists :) And if tequila doesn't work, then ummm I'm not sure what comes next, but maybe that's why Amsterdam exists

I don't say this to make light of the situation, but just want to point out that I'm not sure that particular issue can be attributed to whatever's going on with your groin, fissure, or whatever it may be. Personally I think if you can figure out the health issue, this one wouldn't bother you so much.
Now, having undiagnosed ass pain and undesirable lifestyle changes, I think you're 100% right to worry about those. I was fine all through my 20s and making big time lifestyle changes because of my fissure at 30 still stucked even though I'd already had way too many years of partying hard in my rearview.
I think I recall you saying before that no doc had ever been able to visualize your fissure, and of course you don't have pain during BMs. Forgive me if I'm forgetting something (I take Valium everyday and it's not that great for my memory :)), but why all the diet and lifestyle changes? Are the spasm-like pains the primary symptom? If so there may be ways to control that without making wholesale changes to your life. I mean if you're having spasms for reasons other than a fissure, then it's possible that all the dietary changes in the world won't make a difference. Maybe there's just some pill you can take that'll manage the symptoms until you get it all sorted out, right? I would start from scratch and throw out the assumption of a fissure if no one has ever seen one. Sometimes you get the best perspective by discounting any preconceived notions -- if you tell a doc you likely have a fissure, odds are good he'll lean toward that diagnosis whether the symptoms truly fit or not. Sometimes you've just gotta give a new doc a clean slate to work with.
I had off and on bouts of peripheral neuropathy last year and some of what you're describing does sound potentially nerve related. Nerve pain is usually of a prickly, stinging, almost electrical nature, and is often poorly localized. It can sometimes affect both sides of the body, but more frequently affects only one side if it's due to nerve entrapment. It's seldom dull or sore feeling. So that stuff going on in your groin through your leg I'd think could maybe be some kind of pinched nerve or nerve entrapment. But the lower abdominal tenderness doesn't necessarily sound like nerve pain to me.
Granted we're all just kind of guessing at this point. You're a student, I'm a computer engineer, and none of us have the tools necessary to really say much for certain. Are you open to seeing another doc to kind of get a fresh perspective on everything? Getting a diagnosis sucks because most times it's a process of ruling things out one by one: doctors are better at telling you what you don't have than what you do have, and it's only by slowly narrowing the spectrum of possibilities that they eventually figure things out. If you've been scoped a few times already and no one saw a fissure, plus you don't have the classic symptoms, then it's unlikely to be a fissure. There are other things they can test for and rule out. For instance an abdominal/pelvic CT scan or ultrasound could rule out any of organ issues. A MRI may visualize muscle damage or nerve entrapment caused by a herniated disc. There are also spasms of the internal anal muscles (not the sphincter) like levator ani syndrome or proctalgia fugax (these feel like a charlie horse in the ass) that you can take drugs and do physical therapy for. I guess what I'm saying is I'm positive that whatever it is can likely be cured or at the very least managed, but the first step is getting a diagnosis that you have some level of confidence in.
BTW I've been pretty down at some points in the past and have entertained thoughts of suicide before. I could never follow through with it because I'm scared. But I won't lie, the thoughts have floated through my mind every once in a while. I've tried SSRI antidepressants in the past and didn't like them (although lately I've considered giving them another try since it's been about a decade since I last took them). But they do work for some people and there's nothing wrong with using them. Personally (and I know this is probably a provocative thing to say) when I feel like s**t I smoke a joint or two. It chills me out and helps me cope. And it doesn't make my ass hurt like alcohol does :) I'm not advocating that everyone with problems go out and smoke pot, but what I'm saying is to find some way that works for you to cope and ride out the storm. Being stoned or being on antidepressants sure as hell beats being dead, right?