Has anyone's child had an allergic reaction to their vaccines? What happened, how long after the vaccine, what was the emergency treatment?

My son has two relatives who had life threatening reactions in their first year, one died -28 years ago- the other can't take any vaccines ever -aged 26 now. His reaction was he puffed up to the point he couldn't move.

We're going for his second set of vaccines Tuesday and I've already requested non thimerosal containing vaccines where possible and we'll be extra observant. But what I'm concerned about is if his reaction is so tiny we don't notice, or if we do how quickly does treatment need to be administered to prevent serious harm or death? Of course I'll call 911 as soon as I see any symptoms! His first vaccine he cried for hours after and had a very mild fever perpetuated by his inability to calm down -so was it really a fever or his being exhausted...

Any experiences and advice welcome, but we do intend to vaccinate our child unless the doctors say it's safer not to.