Shaky and tired 3 days after stomach upset

Age- 31
Sex- F
Height- 5'7"
Weight- 150lbs
Race- White
Country of Residence- US
Any existing diagnosed medical issues- IBS, PCOS, depression, anxiety, autism, ADHD, borderline HBP
Any current medications/doses- 0
Any drug Use (including usage of marijuana)- No
Smoking Status- No
Duration of complaint- 5 days

Issue you're having - 5 days ago I started having nausea and not quite diarrhea, more like slightly loose stools 3-4 times a day. I did the usual, thinking it was an IBS flare up. My stomach slowly is going back to normal and I began eating BRAT + drinking electrolytes and water, and now slowly introduced new foods. I have an excess amount of gas, but that's normal for me after an IBS flare.

My issue: I am so weak and shaky. This has never happened before unless I had severe vomiting, and this time I did not (thank God). Like, sitting at my desk, and I feel dizzy and shaky. What might be the reason, and should I be worried? I have plans I cannot cancel in a few days and I fear I may faint during them.

(Cross posted.)