Hi and welcome to HCM.
It can be STD
. This is very possible. It is obviously bacterial infeciton but you should find the exact cause and then it can be trated by antibiotcs. YOu should do swab urethral test before these lumps spread.
Also inform your partner about it,she must be treted as well. Other possible causes are allergies, irritation or viral infection ,but you must rule out STD as I said.
WIsh you good health.