First, You would not remember a seizure.

Second, Many concussions never have a knot on the head.

In looking for information about sneezing and concussions, there is nothing available.

You may have strained the olfactory nerve so it is hypersensitive. I suggest you forgo alcohol for a while. Your brain needs to recover.

You really need to consider getting health insurance. Your lifestyle sounds like it has plenty of risks with potential for needing health care. Otherwise, you risk an injury that leaves you in a painful state, that requires better care than one can get without insurance. You are already experiencing head aches. Head aches are not treated in ER visits and only ER's have to treat you even though you do not have insurance.