Still no answers

I got a rapid covid test this morning just to rule it out since I still don’t know what’s wrong – $175.00 later and it’s negative! This is good but also in a way I was almost like well if it’s positive it all kinda makes sense? But I am glad I do not have covid,

At this point I am welcome any and all opinions / medical advice on what may be going on with me- I will list my symptoms below:

-fatigue that began last wedneday (falling asleep driving to work, completely exhausted and ready for bed by 8:30 every night, no motivation to do anything)

-late period by 12 days- normally I am regular, but have had multiple negative pregnancy tests including a blood hcg

-nausea & puking in the mornings (started this past wednesday)

-lower back pain (started 2-3 days ago, worsening)

-burping a lot

-diarrhea (only for one day- other days lots of movements in morning)

-random dull ache lower abdomen – not consistent cramping though

-headaches (started last night, have one today)

Again, any help is appreciated.