Weird muscle spasm?

Hi everyone. I have a question but I’ll fill you in in my chiari first. I’m 21 and had no symptoms until I had my son when I was 19. I have migraines about 3x week, I’m always tired, always light sensitive and sometimes see halos, I get dizzy spells a couple times a week, and have blacked out a few times although that hasn’t happened in about 6 months. I saw a neurosurgeon a few more things after my diagnosis in 2014 and decided against any treatment. To my question though, today I was being more active than usual and play fighting with my boyfriend. Out of nowhere it felt like I had an extremely painful muscle spasm in the back of my head and it triggered a migraine 10x worse than my normal ones. Has anyone else experienced this or have any advice?

Sometimes the back of my neck will feel kinda tight for no reason and with a sneeze or laughter it tightens up a little more and every now and then will lead to a headache. And if I'm doing any kind of strength training with arm, shoulder, or upper back muscles it feels like my muscles instantly decide they don't feel like working and my neck will get that same tight feeling. I talked to my Dr. about it and she encouraged me to keep moving and exercising and to pay attention to moves that cause pain - then back off and consider reintroducing that movement with a lighter weight or no weight at all. She prescribed flexirol to use as-needed when the tightness won't release with ibuprofen. Hope you can find some relief soon!