Hi Aahleigh1989.
Been there, done that! Suffered hip pain for 22+ months in 2002-2003 out of nowhere. Had previously found out I had an injury from childhood, and this caused this. Went through 7 sacro iliac joint injections altogether, 3 in 2003-2004, 4 in 2010.
When I became pregnant in 2011-2012, needless to say I ended up on crutches etc etc etc.
I won't go into the big spiel, but I know how heartbreaking it is, and it's a pain that is indescribable to anyone that has not had it. Just try to ignore the people who say "I know how you feel", unless they've had the injections (which are just hell on the end of a needle), or have considered surgery, then they can go jump!!!
All I can advise is:
1, maybe see if there is a childhood injury that you were not aware of (I was 16 before I found out about an injury from when I was 2).
2, hot water bottle!!! Sounds basic, but funnily enough did help.
3, maybe try for another injection, if it works, try to build up your hip/back strength as much as possible during the 6-8 weeks you probably have before a reoccurance.
4, don't let it put you off going again. I'm 14wks with 2nd baby, absolutely terrified about the next 26+wks and all after it. But I decided that I wanted another child, so I've taken the chance (I might be slightly mad 
)
5, FIGHT!!! Fight everyone, to get the help & support you need. Start with your GP. I had a great GP, but still had to go to 3 different consultants before I found someone that a: believed me, & b: actually helped.