Middle of the night IBS

Hi everyone-I'm new here. Working on getting a proper diagnosis and hopefully some help.

I'm a 35 year old female that has always had issues with milk products causing painful bloat and then diarrhea. I also have had issues with constipation for years.

But for the past 7 years something strange has been happening. about 3-6 times per month, I will be woken up out of a sound sleep, usually after midnight but before 4am, with horrifically painful lower intestine cramping. I have a very high pain tolerance and these cramps have me moaning and doubled over. I typically drip with sweat and cannot stand up. I sit on the toilet for about 5 -10 minutes, pass some diarrhea, and experience some relief. Then I go back to bed and the process repeats itself every hour or so until I finally release the last of the diarrhea. about once a month while this on the toilet during one of these episodes I vomit. I do not have any of these incidents during the day. Ever.

Obviously being up all night leaves me exhausted and is interfering with my ability to function during the day.

The doctor keeps saying this is constipation related and to take miralax. I am concerned it's more than that.

My medical history involves the partial removal of my thyroid due to a tumor, spinal fusion, and polycystic ovary syndrome/insulin resistance

Can anyone share with me any information related to these middle of the night episodes? Any thoughts? Questions to ask the doctor?

I would appreciate any information possible. Thank you so very much

I don't know really? If I think about the most recent episodes, both have been after having very high fat greasy dinners.