Is this more serious than just heartburn?

I have had heartburn off and on since 2007.  Recently (past 4 months) it has been really bad.  I was on protonix for 3 months and got no relief.  It gets so bad some nights that I cant sit, lay down or stand up without tasting acid in my mouth.  I would say that i get heartburn at least 5 nights or more a week.  Ive tried taking Pepcid AC, TUMS and Protonix none of these even touch it.  More recently i now have pain just below my ribcage/above my stomach that feels almost like a muscle strain but its constantly there and hurts more when i bend over or sit down.  What should I do?