Upper Ball Joint came out while driving

Time to change mechanics if he told you there pressed in and held with a clip.Unless you control arms have been changed out?

Yep!! This is probably (most likely) why they came loose, you "stripped" the streads, time for another control arm or arms if you did both sides that way, if you had the new ball joints in your hand, you could have seen they were threaded, this should have given you a clue right there, then if all else fails, ask the mopar guys on these boards 1st.