What Causes Ulcers In The Inside Of The Lip During Periods?

I get an aphthous ulcers on the inside of my bottom lip every time I come on my period. They're very very painful, covering most of the inside of my bottom lip, my lip swells up, my jaw area swells up (only the right side) and I can't eat properly or speak properly because it hurts to much to do so. Lately it has 'spread' (I wasn't aware this could happen) onto the bottom of my tongue and my tongue has swollen up too. I've had various blood tests for all types of deficiency, but they've all come back normal, and I've had two blood counts, HIV - all normal. But obviously this isn't normal. Whenever I take zinc or feroglobin, during the month before the episode, the ulcers still show up but never hurt as much, and aren't as big. So what exactly could it be?