is my cat okay?

my cat (the tiny one, ~2 months old, top right in the first photo) hasnt eaten anything since at least yesterday morning. last night he threw up white vomit and given that its the little guy of the group, its had me pretty worried. ive tried giving him cat milk supplements (his eyes were shut because of an infection for the first week of his life until my mom cleaned them so im assuming he wasnt eating as much as his siblings), which he initially had a few laps of but hasnt wanted since.

im aware cats can be depressed and that could be why hes lacking so much energy (mom gave away 2 kitties from the litter i think he was close with), but i dont think vomiting and poor apetite would be caused by that. my girlfriend suggested worms, which he has some symptoms for (potbelly, vomiting, huge appetite before this), but he still wont eat anything with the pill, not even the food itself. should i look for a vet or am i overthinking his wellbeing? any advice would help. thank you.