Hello, I Am 36 Weeks Pregnant And All Day Today

Hello, I am 36 weeks pregnant and all day today I have been having very loose stools that look very tarry , I would like to know if this is normal and should I be concerned only because I feel sick and dehydrated. I can't seem to eat anything either, everything seems to make my stomach upset or make me feel nauseous, in this case what should I do ?