2003 Dodge Ram temp gauge

My 2003 Dodge Ram 2500 Hemi 4x4 Heavy duty temperature gauge rises to the H and then drops back off to normal. It will do this with in about 10 minutes of driving. doesn't matter what speed i'm going or up or down hill. Always with in about ten minutes it does it. I've checked all fluid levels and verything is where it should be. It's been doing this for a couple days now. I've looked online for answers and have came close to finding the same problem as my truck but most other people say when there temperature gauge rises it starts blowing cold air, my truck does not blow cold air out of the vents when it spikes up. I've felt my radiator cap after a drive home from work one day (about a 10 mile drive) and it wasn't extremely hot but warm. Now just the other day my check engine light came on and is still on.. Any ideas on what's going on? I've been told it could be a sensor problem, T-stat problem, water pump problem or a head gasket problem... I don't know where to start looking. Any help is appreciated. Thanks...