This needs looking at. Does your college have a health/wellness centre with docs who can take a look?

Looking at your previous post describing the lump, 1.5cm isn't terrifyingly large for a lymph node, but it is bigger than what one might ordinarily expect, and if it is worrying you and seems out of place, then it should be examined. Given the timeframe, it may not be a simple infection, but there is a multiplicity of things it might be, and so the various options need to be ruled out.

Can understand why you might be concerned about lymphoma, if you Googled 'enlarged lymph node' and 'weight loss'. Yes, weight loss can be part of the 'B symptoms' associated with various manifestations of malignancy, but even if you've cut down on gym time but are just doing loads of vigorous shagging, walking long distances between classes, scuba-breathing through your vape, or any number of other things, then you might be shedding a few pounds purely due to lifestyle.

However, the cost/benefit of getting the thing checked, whether the benefit is in the form of some simple reassurance or some further examinations, is very clear. As soon as you can manage.