I suggest you get a home blood pressure kit so you can check and see if these symptoms are related to a sudden rise in blood pressure. They also may be related to a neck position that you only do when doing these exercises.

Focal head aches can be vascular spasms. They can be almost thunderclap in presentation. The blood vessel spasms tightly causing a focal and intense pain. They are most common in the temple area.

Push ups and pull ups are not a way to gradually build up your tolerance for exercise. A brisk walk but with a careful focus on a soft foot plant may be better. Or a stationary bike. You do not want to raise you pulse by more than 25% or so of normal.

I would not worry about a bleed. The pain would be intense and not go away. You would likely have other serious symptoms, too.

btw, 10 moderate concussions does not include a lifetime of hockey sub-concussive impacts. They can combine with the concussions to leave your brain very sensitive to movement.

At your age, your brain is starting a period of lower tolerance to all kinds of stressors. You would do well to take a broad approach to reducing risk to your brain.

My best to you.