Honey helps with lemon. Drink orange juice for vitamin C.
I would call your doctor to check with a nurse. I'm pretty sure Theraflu is OK but it's been since 3 years since I was really sick and pregnant. Things change all the time as far as safety, your Dr/nurse will know best. Most places give you a safe med list at your first appointment but I'm assuming you haven't had you first visit yet. Hang in there and try to get a lot of rest.
Take Tylenol if you have fever. Tylenol is safe in pregnancy and fever is dangerous for fetus. Nasal saline is totally safe and good if you're having nosebleeds.