I'm so sorry that happened to you omg! What a nightmare. Unfortunately, these things are uncontrollable and unpredictable.
I am quite surprised that your boss and colleagues have started to make a joke of the incident, as its clearly a distressing position to be in, and you were sick! What's so funny about that?
If it was me, I would also be VERY close to resigning immediately. The fact that you held your head up high and went back to work the next day takes GUTS. Seriousss guts. Not everyone would be able to do that.
Now, is this job replaceable, e.g. a short term retail job? Or is it a long term career-setting job? That will determine whether you should consider resigning or not.
But honestly, just like high school gossip, this will probably all die down in a week or two's time anyway. You can either ignore it until it goes away, or you can own it, and take the power away from them. Discuss it candidly with them, without fear or shame. For example, when you hear them laughing, laugh with them! Say "hahaha I still can't believe that happened to me! My gosh, I felt soooo ill!" and just speak about it as normal. Also over-emphasise how ill you felt and how horrible it was, so they hopefully feel guilty about laughing. Once they hear you speak normally about it, it takes away the "fun" of it for them, and makes them look dumb for acting like children and finding it so funny.
Good luck!