Diet is important. The system needs food and the right nutrients to recover. Read up on this, as there's an extensive amount of information to read. If TLDR, then go high on the protein, go low on the carbs and cut out simple carbs and sugar. Make sure you get the micronutrients as well (electrolytes like magnesium, potassium, etc. etc.)

Rest properly. I sleep poorly, but I also only work out very heavily three times a week. The system need rest to recover.

It sounds like you're not differentiating different types of activities. So we don't know how often you do them, or anything else. Whether you took lessons or professional guidance or just jumped in the water and starting splashing hard around you, or what. Calisthenics / bodyweight training is very powerful, well-rounded as it will strengthen your ligaments and tendons as well as your muscles. In contrast to weight training (stay the hell away from machines unless you are in physical therapy), calisthenics strives for functional movements, which use several muscle groups in conjunction. You can find a lot of material on this online.

Tennis elbow I can't help with, but running pains are very normal. I have over-pronating feet so always suffered from knee issues and shin splint. But most runners I know have issues like this. Muscle imbalances mixed with individual mechanical quirks like flat feet (me). The muscle imbalance part is even more common, and fixed by educating yourself and doing complementary exercises. For example, exercises like squats and lunges help balance things out against the evils of running alone.

Doctors are a pain. As someone said, find a sports one. Otherwise you'll risk hearing 'Okay, stop exercising for 2 months and take aspirin every day.' I hate it when doctors do stuff like that (ignore the individual person's goals rather than work with them).