3 months ago I hit my head so hard that I fractured my frontal sinus bone. This resulted in a concussion and I was feeling symptoms of PCS (light headed, nausea) for about 2 months, then I started feeling pretty much normal. I started feeling slight symptoms such as light-headedness and nausea again a few days ago. This started the same day I began weight training again. 2 weeks after the concussion I tried to lift weights for a few days and this made my symptoms worse, so I stopped. Although this could be a coincidence, I think there is a correlation, since no other factors such as diet or stress have changed. Why would weight lifting cause my symptoms to come back? How long should I wait to start weight training again after I feel symptom free? Can I do light cardio exercise? Any diet recommendations?

Just to let you know, I have had 2 CAT scans and seen a neurosurgeon. The doctors did not find anything wrong on the cat scan (with the exception of the fracture)