long term sick after losing a twin

background info: last year i had a mmc and nearly died. 3 days spent in hospital and two blood transfusions. Flash forward to april this year i took a new job and found out i was pregnant. before i started i was put on bedrest for two weeks as i had one yolk and one empty sack. 2 weeks later there were two heartbeats. at 11 weeks i found out one twin had stopped growing. at 12 weeks it was confirmed it had no heart beat but the other twin is still growing. so they havent wanted to intervene. My work place were fine and supportive. ive been off work under a drs note for 3 weeks now. when i rang to say i wouldnt be in this week my manager was vile. asked if i wanted to bother coming back, apparently i had excuses for being off, ive been told not to bother ringing again until i can be bothered to come back. I was and still am a health care assistant doing 6hrs with no breaks doing manual handling with heavy equipment. im struggling mentally with another lose, that the lose is still there, the stress of a nasty manager, i can barely walk with the pain in my legs from either sciatica or pelvic grindle, i cant drive because of it and i have a 30 mim drive to work. i also ache, i sleep 12hrs at night and sleep 2hrs maybe 3hrs in the day. my doctor only signs me off for a week at a time and i have to use emegency appointments. Im 15 weeks and i cant go on maternity until 28 weeks which i didnt want to do but apparently it can kick in when youve been on the sick for x amount of time. Please any advice on what to do or how i can get longer off a time.