When tou are shipping freight to your customers, the cost of making that delivery is an expense that comes out of your ledger as a debit. This is considered a selling expense and is known as freight-out. When you make a purchase and the supplier bills you for shipping, that is referred to as a freight-in.
It depends on what causing it. the only thing I can say is to drink plenty of fluids but I would recommend to go see a doctor, if you are unsure or worried.
