What Causes Painful Lumps With Clear Discharge On The Arm?

i hav had 3 lumps on my arm 1 of wich is causeing pain down my arm to my fingers painfull when i move /wigle my fingers i have reocureing clear/ water pus come out after i bath in salt water i think it started out as a bite with the pus returning is that a good or bad thing thank briab