Very normal, especially with high quality gh. Try backing down to 2 or 3 iu and see if you feel better. If you do, run that dose for a while before upping it again, test to see if you tolerate that, repeat until you are at the dosage you want or the highest you can tolerate.
completely normal and you should have done research on hgh before using it... im not trying to be a dick here but thats really basic knowledge on it, which means you didnt do much research to start with, which is a very bad move when using anything man