Morning sickness

Need some advice....my sister is roughly 15 weeks and I am a few days behind her.

My sister has suffered with bad nausea, had a couple of weeks off from work. We all told her she went back too soon (she's stubborn) over the last couple of days her sickness has gotten much worse.

I'm really worried as she's shrugging it off.

Have any of you had it where the sickness gets worse rather than better?

I've had horrendous morning sickness, ended up in hospital but just like everyone has told me it started to get better at about 13 weeks. I'm really concerned about her and she doesn't seem to be bothered about getting help apart from moaning to me.

Any advice would be amazing xx