My girlfriend got diagnosed with BPD before we started dating. She was taking meds for about a year, then we started dating. There were a few depression episodes but we worked it out.

Three weeks ago she switched medication. Since then every time we hang out something little happens and she switches completely. She shuts off completely cries, wants me to take her home, sometimes we talk it out and she feels better. Sometimes we can't. 

This weekend we hung out and it was great. This morning I wake up to loving texts and then 2 minutes later it switches and she shuts off. We just got off the phone and I was trying to talk with her but couldn't. 

It's starting to get to me and I don't want to break up with her because of these episodes. I just need to understand and how I can help. I thought it was due to switching medication and I am sure it is but I don't know how to help her through it. 

Advice? 