What did I experience? heartbreak or what?

TL;DR: Thought she broke up with me, then slept very little, can’t drink, felt like can’t really breathe or some weird feeling. Was it heartbreak and was I in love with her?

Hi guys can you tell me what did I experience? Was it heartbreak? Panic attack? (I had very few relationships before and they weren’t long, so I am pretty inexperienced in this)

Tried to meet up with this girl again, but no show, tried all contact info and no answer. Waited two hours and still no show and no answer. Went back home and I was thinking maybe she doesn’t want to see me anymore? Did I do something wrong? Is this the way she saying goodbye?

That night I slept for three hours, woke up and later slept another 1 hour. Whole day I couldn’t eat, ate very little, had to remind myself that it’s been 7,8 hours since I last ate, later tried to eat and still ate very little. Couldn’t drink, when I tried to drink it felt like something in my throat and I just can’t get the water down, it was a weird feeling and I was a little thirsty. I felt like I need to go out and get air, can’t really breathe or some weird feeling.

2.5 days later I texted her again, she said her phone was messed up. (Don’t know if totally true or not) Then immediately I felt better, can sleep can eat. What was that? Heartbroken? Panic attack or what?

Other things I should add is that I liked her but not a very strong feeling, one misleading text she thought I was leaving her city, she took taxi rushed over and was in her Pajamas, she was really worried sick that I was leaving, then I know she got very strong feeling for me but never told/showed me. Then after that I had a much stronger feeling for her, then couple days later she didn’t show up. (Like I mentioned earlier before)

Also she seemed to be really in love with me, and I was influenced by that greatly then I think I fell for her too. (I only liked her some before and probably would have never used the love word) So was I really in love with her? Or only influenced by her and didn’t really love her? She didn’t have all the qualities I was looking for as a lover, until she really fell for me big time.

Any tips for relationship beginner like me? (for next relationships, what to say/do and how not to get hurt or hurt others) I am actually a little older and got almost no exp, never fell in love until now and I am not sure what this is. Thanks for your help.