I kegged a RIS a few months ago and planned on letting it sit in basement around 60F for awhile before ultimately carbonating it further and drinking it. When it went into the keg the gravity was around 1.030 down from 1.10. I periodically checked to make sure it was holding pressure and never had a problem. Today I put it into the kegerator and it is acting like it is pressurized way above normal. I guess it may have gotten shaken up a little bit in tranfer but not like we rolled it down a hill. Hooking it up to a gas line, the beer shot back into the gas line despite about 20 psi on the line. I have disconnected the gas, tried pouring off some through the beer line and pulled the pin several times to try and off gas it a bit but eventually it starts shooting foam out the pin. Also whatever I pour off is almost pure foam and coming out rather violently. Any chance this is infected? Doesn't particularly taste bad or off. I also thought terminal gravity had been reached or at least very close to it (it had about a month to ferment in the carboy). Any suggestions?