I Had A Rather Large Blister In My Mouth On

I had a rather large blister in my mouth on the back right cheek area. I finally pooped it - the bitter taste was aweful and I tried to spit most of it out. That was 2 days ago. Yesterday afternoon I started having severe pain in my upper thighs and butt. I hurts to put weight on either leg. I was hoping these two things were not related and if they are - what can I do? Should I see my doctor? I have not worked out for over 3 weeks.