Strange things going on in my head

Since a young age probably teens I have always tended to have a weak left arm well always used right arm / hand for things. Before I had my back surgery done always used left arm to hold myself up to hold me up and needed to do things with my right most of the time. Then I had the operation and I slowly started to use left arm and hand for something’s, but still tended to use right.

Anyway recently I came home from work and developed a banging headache as the evening went on, I put it down to busy day and tiredness and went to bed and took a paracetamol slept it off. I woke next morning fine didn't think anything of it went down for breakfast and mum had made me cup of tea and placed it so could get it with strong hand as normal, but for some odd reason I moved my left arm and went to get it with hand and picked it up with no problem and I have never been able too do that without a struggle.

I am wondering if headache was something reconnecting in head because I can still do it and its improving all of the time. I went back to work after the event and was really pleased with myself and people picked up on it. I said I have something to show you and I proceeded to pick up my desk and the response was you can't do that !!!!!!!! I just have I said