I wore my retainers last night after some time of not wearing them & while the top retainer fits great, the bottom one is a bit tight. i wore it through the night and my gums are swollen but not painful today. is this normal? should i continue wear?

Your mandibular teeth have probably shifted during the extended time of not wearing them. You should consult with your dentist or orthodontist to see if the they can be adjusted. Wearing too tight retainers can cause damage to the bone surrounding your teeth.

Retainers were made to your corrected position. Not wearing them allowed relapse. You need to see your Orthodontist to assess viability of the retainers. You need to be flossing daily to prevent gums from swelling. Don't force the retainers as that might increase damage. But see Orthodontist ASAP to prevent further relapse.