Getting 3-bet with small pairs is super +EV if you call when you have implied odds, because your opponent is significantly more likely to felt than if they had put in the first raise. If you are getting 3-bet a lot, you should just 1. try not to make your initial raise very big (so the 3-bet shouldn't be too much to call) and 2. always have a full stack - and hopefully the 3-bets are coming from people with full stacks as well, so it will be profitable to call them.

If you're really getting 3-bet relentlessly though, limping isn't bad. You should be trapping more in those games anyway.