Much more likely that what you are experiencing is a migraine attack and not a new concussion. I was not there for your boxing, but it takes A LOT of force to physically stretch the nerve cells in the brain enough to cause a concussion. If you have what I have, sudden movements can trigger an overload of a vestibular input that causes a migraine attack that can honestly be even MORE miserable than a concussion (but it is not a concussion, and you would not have any long-term brain damage). Please see a headache specialist, vestibular specialist, etc. to get checked out.

I, as well as some of my doctors, was convinced I was getting repeat concussions for years. They were migraine attacks. You need to find out if this is the case for you because there are ways you can treat them. There are abortive and preventative meds you can take, along with vestibular PT you can do to reduce your sensitivity over time.