How much vomit is normal?

Ma

My daughter normally has little spit ups here and there, nothing major. Sometimes big spit ups but again they seem normal. She woke up at 1:30am for a feed and that was all fine, I burped her and changed her nappy.

She then had a massive vomit all over me, it didn't seem forceful but it stunk like actual vomit instead of the normal sour milk/just milk smell. I had to have a shower because the smell was so bad. She then vomited on my husband, not as much but still a large vomit. He showered and I gave her a wipe down (it's 3am here so I'll bath her in the morning). I tried to feed her because she normally feeds to sleep and I figured her stomach would be empty but she gagged on the nipple shield which she's normally fine with. I rocked and patted her and as she was drifting off to sleep she gagged a couple of times but didn't bring anything else up. I'm a ftm and I'm freaking out a little. She's 3.5 weeks old and breastfed, I'm currently on antibiotics for mastitis so I don't know if that could have caused it?