Faint at the slightest pain?

I've never been too bad with pain until just recently, i've had tattoo's and piercings and they haven't bothered me, but just now the slightest pain sends my head spinning my hearing goes fuzzy and I p out, it's not even severe pain, from stubbing my toe to stomach ache. I just banged my knee on the desk and I could feel myself going. Is this something I should go to the doctors about, or is it just something? I've recently been put on betablockers and my mum has an overactive thyroid gland which can be hereditary, could this be it?