Lump!!!!

I have this lump on the inside of my upper lip in the gum. It's been there for a few days and is really soar. I would just assume it's a mouth ulcer as I've eaten very salty sugary food lately and have been really stressed out. However I've also got with a boy and kissed a lot.. He's never kissed anyone so I doubt it's to do with him. Can someone just re assure me please??