When my kitty died two and a half years ago I awoke every day with this same kind of feeling. Just before falling asleep the sadness arose every night, too. My grief was over the top. Eventually, after adopting four kitties, they have kept me so busy that morning/evening sadness left me.
So, here it is, again. Same feelings. Different reason.
Obviously it is finally hitting me. I've been too busy and stressed out, going through all the tests and doctor's appointments. Today I'll be by myself. Nothing to do. No appointments. No having to drive anywhere. No relating to other people. Just me and my cats. Naturally my body knows this and has triggered letting these suppressed feelings out.
So perhaps today I will wallow a little bit.