Shoulder pops all the time. Starts to ache after exercising. But doesn't hurt during exercise.

The pop or crack is usually tendons or ligaments moving over bones. So long as you don't have to force it it shouldn't really be anything to worry about. I would go to your doctor and make sure that it isn't anything to worry about.

So the aching pain is my tendons being sore for grinding against the bone? See I'm in the army and use my shoulders a lot.. I just don't want to have problems with it in the future

Why Do Shoulders Snap or Pop? Howard Luks, MD Westchester County NY
Also, Google dislocated shoulder to learn about what to do if you dislocate it (with the help of others). Not all doctors agree with putting it back yourself, but a soldier out in the field doesn't have a lot of options, and countless people do it with no ill effects.