What to expect: ectopic

Found out yesterday that I was having an ectopic pregnancy of unknown location and not a miscarriage.

Current Issue:

I am scared that I won't know what pain is the concerning type of pain. I've been told by a friend that days 5-9 will be the worst of it, but idk how to mentally prepare for it. I am worried I wont know what's concerning because I dont know where I'm supposed to be having the "scary pains" some people have said shoulder some say abdomen, i just dont know. I called my OB but the nurse called back and kind of just asked if I was having any current pain and how much I was bleeding, which I'm not having pain and I'm currently just spotting. My anxiety has been terrible and I dont know what's common to expect. I have been having itchiness on my skin but I get that with anxiety too. It doesn't seem like a rash or anything visible, so im thinking it's just my anxiety. I haven't been able to take my anxiety medication due to the interactions my current one has with the Methotrexate, I'm waiting to hear back from my other doctor about switching to Xanax for the time being as there is less interaction. I'm basically terrified for the pain. On a scale from 1-10 what was your pain like and when did it start or end?

Background:

First my doctor thought I was miscarrying when I went to the ER on 4/22 due to heavy bleeding with clots, what felt like braxton hicks contractions, and dizziness, all after a positive home pregnancy test. My first beta was 4/22 and 157, second was 4/24 and 114, that was all consistent with miscarriage.. well we did our third beta was yesterday 5/1 and it was 177. Was sent back to the ER got new bloods done and another TVUS. Well nothing visible on the US, no heartbeat to find, no baby, sac, fetal pole, nothing. My doctor said at this point it was most likely ectopic, since it isnt doubling or acting normal on bloodwork. We have struggled with infertility since having our baby girl. We have been trying for years with no luck. I wanted to wait it out until they could confirm since I have annovulatory cycles and I was hoping maybe I was just too early. She said adding a ruptured tube to our list of issues would be the worst thing we could do and advised this chemotherapy route.

So I got Methotrexate last night. One shot in each of my arms at the same time. So far havent had any symptoms other than feeling fluish, some mild nausea/dizziness and feeling very flushed/sweating, also a bit period crampy on the left side only but not untolerated by any means. We were told I need to go back in on day 4 (sunday) for a beta check and then again on day 6(wednesday). I am so concerned that I don't know what to expect and that the ER didnt do the best job explaining what to look out for other than come back if I'm soaking 1 pad in 1 hour.

If you read it this far I thank you, I havent told any family member or friends outside of my husband and the one friend I have that went through it herself.