can be completely normal. it can be problematic, but it is not common... It is also common for allergies to flare up more when you are pregnant. You can take REGULAR benedryl. Just the basic stuff.
Talk to your doc at your first visit (assuming you haven't seen one at 5 weeks yet)
Hopefully your body gets a little used to it & adjusts accordingly. my itching has gone WAY down, but I still sneeze ALOT (not as much though)
My feet itched really bad during the first trimester but I used Vitamin E lotion and it helped alot. Like the above said it should go away, but if it doesnt talk to your doc when you go for your first checkup.