Hard very sm salivary gland stick up and is painful when i press the underside of jaw doesn't happen on other side of mouth though what can this be?

Blocked duct: I will give you one of many possibilities. The salivary gland empties into your mouth through a duct.If anything blocks the duct the saliva will back up. Trauma or a calcium "stone" can block it. You can try to reopen by sucking on sour sugarless hard candy for a day. Not going to harm anything. If you have any doubts check with your physician or dentist.

See below: The gland could have a blocked duct and a possible infection best to get this looked at.