I get very similar symptoms (pressure in the head, eye pain, blurred vision, spaciness, neck pain, tinnitus, etc., all of which can last for days or longer) from any exercise beyond a couple minutes of gentle walking. It drives me crazy, since exercise is widely regarded to be one of the best activities for concussion recovery and brain health in general, but for 3 years it's only made me far worse and caused countless setbacks. NUCCA chiropractic has helped my symptoms some but doesn't seem to fix the underlying issue for me either.

My concussion doctor can't fully explain it, but his theory is that it's a blood flow issue, as you suggested, since the injured brain can lose the ability to properly regulate cerebral blood flow. I haven't found a way around it either. My doctor has told me it's possible to retrain the body to regulate blood flow to the brain via the standard exercising below symptom threshold with an extremely slow increase in intensity or duration. I've been through several rounds of physical therapy as well as following this protocol on my own, and have found that I'm able to slowly work up to walking 20 minutes or so with only moderate symptoms but anything beyond that will inevitably cause a major setback after which I have to start all over again.

But since you're able to run and do bodyweight exercises I feel like you're in a better position for success with that kind of protocol. So, have you tried doing your weightlifting routines with extremely light weights and increasing the weight very slowly over the months? I don't know why it doesn't work for me but maybe it would for you. And have you tried physical therapy? My PT helped me with finding the right posture during exercise, thereby minimizing symptoms (though optimizing posture only did so much for me).

In terms of meds, I've been on and off various ones (trazodone, amitripyline, gabapentin, etc.) and none of them have affected these symptoms.