mamakim, sorry you are feeling so bad. I was right where you are now a few weeks ago (am now 28+3) and I felt wretched too. It was a big shock as I was never that bad with my 2 DSs.
Agree about the sinus pain, might be an idea to try steaming your head with some childrens olbas or karvol - it really does help. Also have plenty of hot drinks, preferably not tea or coffee as the milk stifles the steam. I have hot blackcurrant or orange squash which is oddly comforting. I've had sinusitis 3 times since I got pregnant, the first time being in the middle of the first trimester.
I would also make an appointment with your GP as if it is your sinuses and you are flying anywhere on holiday the flight would be really painful.
Afraid my only other recommendation is to take the opportunity when your DS is asleep to have a long steamy bubble bath (not too hot, put the hot in first to steam the room up then the cold) as not only will it help you relax, it will also help your head.
Incidentally, I found out I am expecting a girl this time, I suspect that's why this pregnancy has been so much harder different.
Hope you are feeling better soon.