"아픈거 싫어했어 꼬집으면 안돼."
The phrase looks wrong since "했어" cannot come in the middle of a sentence this way.
More contextual informal is needed to know exactly what is meant.
As it is, the sentence may be corrected in one of the following ways:
1. 아픈 거 싫어했어. 꼬집으면 안 돼. [He/she] hated any pain. You shouldn't pinch him/her.
2. 아픈 거 싫어해서 꼬집으면 안 돼. [He/she] hates any pain, so you shouldn't pinch him/her.
3. 아픈 거 싫어하니까 꼬집으면 안 돼. Since [he/she] hates any pain, you shouldn't pinch him/her.
* ~해서 = verb+(아/어)서: expresses a loose cause and effect, or sequence of events.
* ~니까: gives a clear reason for what follows (because/since ...).
#1 sounds strange. #2 is okay, though slightly confusing. #3 says the same thing as #2 more clearly.