I Had Diarrhea Friday Night. Was Fine Saturday Until Late

I had diarrhea Friday night. Was fine Saturday until late in the afternoon, when I developed a headache, dizziness and nausea. This has continued through today, Sunday. I went to an urgent care facility, and they did an EKG and some blood work and a checkup, but said that they did not have access to do a CAT scan because of the weekend. They ruled out infection and heart issues. I have type 2 diabetes, COPD, CHF, Sleep Apnea, Psoriasis and some ruptured disks. I was sent to the ER, but after many hours waiting to be seen, my headache was getting worse and I had skipped medicines and meals, so I left. The symptoms have eased up a little after eating and taking Ibuprofen, but am still a bit light headed and nauseous and still have a bit of a headache. Any suggestions as to what might be causing this? Perhaps a virus?