damn - you are one big kid! How did you injure your knee? And what are you doing for PT now?
What is your goal specifically? Normally I would probably tell someone your age to keep it real simple & just stick w/ calisthenics / your own bodyweight type stuff because you are still growing. But sounds like you already grew!
The whole ab thing is sort of overrated-- everyone wants a 6-pack so they do thousands of sit-ups / ab work -- then can't figure out why they can't see their 6-pack and they are actually getting thicker in the waist -- that's because seeing the 6-pack is all about diet.
And just for the record - "screaming in pain rigorous" is a bit of overkill --- because if its that ba,d you may actually be hurting yourself, overtraining or possibly not eating to fuel what you are doing or recovering sufficiently to do it again.
I would start by asking for the following:
1) What specifically are your goals? Strength? Size? Cut up? train for a particular sport?
2) what is your PT now & where are you in your recovery of that / what does the doc say about it?
3) What is your current diet? Can you post this up in detail e.g.
Meal 1: 8 am
1 c oatmeal
2 scoops protein mix
Meal 2: 10 am
5 oz chicken
1 c rice
1 c green beans
etc
Also if you put the whole thing into an online foods program like
www.fitday.com, you can see very specifically what you are eating as far as total cals, & macronutrient breakdown (% protein, % fat, % carbs). Then maybe there are some tweaks we can suggest to get you to a more optimal diet to support whatever is the training you decide to do.
This may appear tedious and why the heck do I need to bother w/ my diet -- if you are interested in developing a strong training program, if you understand now that 80% of any progress you want to make in the gym will be driven by what you eat. If you build a solid base and come to understand how your body responds to the variations in the diet, you will be light years ahead of anyone say in your JV level football team or whatever you choose to do with yourself.
That's where I would suggest to start -- toss any of the myths & misconceptions about diet & training early on & you will develop a base of strength & metabolic response that will serve you extremely well as you are growing and especially when you hit your peak in natural testosterone production in the coming years. And lastly, but not the least, will also go very far to helping you recover from any injuries and further preventing them in the future. Its very hard to recover 1000% from any joint injuries so even just w/ this knee injury you may spend the rest of your life favoring that knee which may result in another part of your body developing how it normally would not to compensate.