Period or pregnancy

Has anyone had what they believed to be their period seemed pretty normal but came 3 days early and then about a week after it stopped started getting nauseated, diarrhea, hot flashes, frequent urination and palpitations? Happens more in the middle of the night/early morning hour then subsides besides the frequent urination. I am not on birth control and did have sex around my time of ovulation last month. If I was pregnant this would be my second pregnancy. It has been awhile since my first pregnancy.

Does anyone have any insight? Could I actually be pregnant?