Yes, a vet needs to attend to this. There may well be some microbial infection going on, as well as a problem with constipation. Bless you for trying so hard for these little guys. It's a tough row to hoe, I know.
i just found kitty dead. she had 3 visits in vet last 3 days. got antibiotics, and some vitamins and glucose under the skin....i wanted to give her some water, but she didn't want....i fought but was too weak and unprepared to win without her mom that she lost so early
Rest you gentle, Little One, dream you deep. Your tiny life had meaning and you are mourned. Your guardian did her very best for you, and you left us loved.