sick all the time and working?

not even sure if this is relevant to my heds but i get sick so easily and frequently with colds, stomach bugs etc. and they knock me out of commission for a long while- on top of already being unwell in general im genuinely becoming concerned my work is going to have issue with me about it soon :( just a casual maybe 3 or 4 hours a week but its all i have left that im able to do really and i dont think im... ready to give up working and some semblance of a normal life at 20. most days i think im fine but ive come to realise i only feel sort of fine on days where im doing absolutely nothing im in the middle of studying to go into a proper job too but at this rate is it all for nothing? i dont think im sick enough to even consider disability really (per the government requirements at least) thanks for reading and any support x