Any detergent or perfumy smells still bring me back, too. And I can absolutely understand adverse reaction to some treatment!
Natalie, you asked if it goes on forever. No, it really will not. There will be triggers that will last in memory...8 years ago, with my first HG, my dad took us out to eat at a local restaurant. We were not telling anyone we were pregnant, and I was trying to will myself to be ok so he didn't suspect anything was wrong. I somehow choked down a hamburger and then spent the rest of the night throwing up painful chunks as I cried and my throat bled.
To this day, I still have that flashback when we eat at that restaurant, but I no longer feel the pain or really any emotion associated with it. It's just like my mind acknowledges the memory, but I'm completely removed from the situation by now. It takes time, but you will get past the physical reaction, and even the intense emotional reaction, to the triggers. I don't know that the memories fade--my 4 HGs all blend into one now, so I've lost lots of the isolated memories, but I still vividly recall the big triggers. The really adverse reactions will fade, leavng more of a momentary stab of wistful memory of that time in life.