This happened to me, I've probably always had mild sleep apnea (always snored, always been overweight, and always slept on my wide) but I went up about 10KG and it got super bad to the point my wife was concerned and often heard me stop, got tested and I had a pretty bad result as far as the rest goes (stopped breathing like 40 times per minute or something).

The good news is I got a CPAP machine and couldn't be happier, now about a year in. My only advise is don't cheap out just get the top model with the features, e.g. you want autoset pressure, not static, the heated hose, and play around to find a comfortable mask. Now I stop breathing something like 0.3 times per hour which is apparently "amazing" you can still have up to 5 times per hour and be considered "OK". Also shop around as the place that tested me, kept trying to convince me to go with a static pressure model to "save money" even after making it clear I wasn't interested in that.. but I purchased my machine from perthcpap.com.au instead and the autoset model cost less than they wanted to sell me the static for. Go figure.

I had a few people I know who didn't tolerate it so well and most of them got non-autoset and non-heated and it makes a huge difference. The mask you use also matters a lot.

The difference to my alertness, how I feel after sleeping, and not getting super tired and needing a nap in afternoons is incredible.

TL;DR: Get a sleepstudy. At least here it's a home test where you just where a machine and a few sensors and takes 1 night.