I havent fully read all the replies, apologies if i cover stuff already said.
Document everything, and dont be shy about it. If he says 'morning sickness should stop in the morning' write it down, along with the time and your reply. Try to stay professional with those replies (hard i know but really important), maybe 'unfortunately morning sickness is rather mis described and can last all day, i can go to my gp for medication' (or whatever, you know what i mean!)
Do you have someone in your work place that you could 'get on side' so when you go back to work and called in the office, bring someone else with you so its not one on one, and you then have a witness to what is said.
If you have d&v, absolutley say its preganancy related, you are more susceptible to illness in pregnancy.
It sounds like they are being really unreasonable and you are being discriminated against, have a look at sexual discrimination as well, you may find there is something in there that is useful.
Good luck!