I've nothing new to add to what everyone else has said, but this sounds just like us too. My 1 year old's had one thing after another (colds, ear infections, temperatures, and most recently chicken pox) since she was six months old, so it's been a busy winter for her! She seems to catch something new whenever she mixes with other children.
We haven't been to any playgroups for a few weeks and she's been very healthy and the happiest she's been for ages, so it's kind of tempting to just keep her away from other kids... But that's a bit sad for her, so we'll probably go back next week. It's a dilemma really; healthy energetic baby or sociable but sickly baby?!
Throughout all the bugs the only time we were prescribed antibiotics was when she had a 'piller-box red' ear infection. I think it depends on the doctor and and varies ever such a lot depending on how they feel about prescribing them. It's best to talk it over with them if you're concerned.