Senior cat has constant "burps"

As the years go by, my old buddy (age 15) and I are getting along pretty well, but I noticed that lately he makes these burping/hiccup/swallowing sounds at a high frequency whenever he jumps up on my lap to take a snooze. He doesn't have any pain or trouble breathing when he makes this sound, but I'm very curious as to what this is. It just happened a few minutes ago, right after he ate some crunchies, so could this be digestion issue? I'm not sure if it only happens after he eats, but I would say that 60% of the time I notice him burping/hiccuping right after he jumps up on my lap. It usually goes away after about 5-10 minutes and he lulls off to sleep.

Is this anything to be concerned about? Junebug seems otherwise healthy and happy. The burping/hiccuping/swallowing noises seem to have started out of nowhere about 2-3 months ago. It doesn't seem to be getting worse. He also has recently developed occasional gas problems which I simply attributed to old aging. But, is this another sign that maybe Junebug isn't digesting his food appropriately?

It should be noted this kitty is extremely sensitive to all forms of stimuli!! ... his stomach included! He's always been prone to an upset stomach. But... is it simply harder for Junebug to digest at this age or is he developing some kind of allergy?

It sounds like he could be having some issues with nausea or excessive salivation. Can you check his teeth to see if there are any that are broken or loose? Has he had a vet visit recently, with senior bloodwork?

Older or heavyweight cats sometimes grunt when jumping. But this doesn't sound like that. Definitely take yours to the vet, so they can check his respiration, heart function and digestion.