Hi there, don't know if I can really help, but didn't want you to go unanswered. It sounds as if this course of AB's hasn't worked, the doctor might try you on a different one. Can you take any painkillers, so you can get a reasonable night's sleep?
Have you tried steaming - filling a bowl with hot water, add a drop of olbas oil then lean over bowl with a towel over your head and breath in the steam. It can sometimes help loosen things up a bit.
Another thing I sometimes find helps is to go for a walk, the fresh air will sometimes make the gungy stuff in your sinus drip out.
Sounds as if everything has got a bit on top of you. Its a long time since I was pregnant, but I had awful MS too, and I know its miserable and exhausting.
I would ask the doctor to sign you off sick, to give yourself time to recover. Once the sinus thing is sorted out you'll probably start to feel better in yourself.
Maybe a nice bath and an earlyish night tonight would be nice, and might help unblock your head a bit. Take care