I noticed the same with mine after almost 10 years. Out of no where my front lower teeth were hurting and I noticed a bit of gum recession. Because of the cost of dental work (and the constant irritating ache) I retired it. I have no idea why it happened and why it took so long to happen, but changing jewelry didn't help at all with mine. 

Gum recession isn't going to cause infection. :S
I would say try swapping out the beads for smaller ones, maybe try the labret stud again but with bioplast instead of metal?

I would personally give PTFE a go, or even glass tongue studs
PTFE is way less hard than titanium/ stainless steel and this will prevent gum recession. Try looking here http://aestheticsbodymod.com/store/ they're able to make you a custom order too.

Also glass is a great option, when i switched the titanium labret stud in my labret piercing with a pyrex glass one i noticed it is indeed more comfortable, for gums too. I have no sign of gum recession, myself.
Have a look here: www.glasswearstudios.com they do make tongue studs in three different types.

I would go see a professional for proper measuring.  A shorter barbell may help you quite a bit, or it may be too tight.  If you can find one long enough, a PTFE labret stud may give you relief.  Otherwise, you may have to retire the piercing or get it pierced further back.