Should I try a total elimination diet?

ashcartwright

my little one is 14 weeks. About two weeks ago I found blood in her stool for the first time. She has had mucousy stool for probably a month or so. The doctor seems to think she has an anal fissure but from what I read I don't think that's the case. She only has specs of blood but it's mixed in with the stool and not streaks on top of it.  They are also very runny. 
Little one is breastfeed only.  For over a week now (when the blood started) she has been waking up every hour in pain in the middle of the night and the only way to calm her down is by nursing.  I have tried bicycle legs (which helps a little), massages, and gas drops with no help. I have also had her on probiotics for three weeks.  She doesn't have any rashes other than a mild diaper rash every so often.  The first 3 months of breastfeeding went great, although she was gassy but not nearly as bad.  She used to sleep 4-5 hours straight through the night. This waking up every hour is taking a toll on me but I'm willing to do what I have to to keep her happy and continue breastfeeding. 
I eliminated dairy 6 days ago with absolutely no difference that I can see. I know it can take weeks but I thought I'd maybe see the slightest difference by now.   I feel like doing a total elimination diet to get her relief and us both some sleep if that is the case.  I feel if I just keep picking things to eliminate it will take so long and I don't know how much longer I can run on such little sleep. 
As far as I know I didn't change my diet around 3 months (except I started to experiment with no dairy) so I don't believe she's reacting to something new. 
Does anyone know if it's common for a baby to not show allergy signs until they are 3 month?
she isn't a very good napper either. For 6 weeks she only napped for 30 minutes and just started napping over 2 hours now and then since she's been waking so frequently in the night. 
Overall she's pretty happy and gains weight very well.   Her poos are explosive mostly though.   She can get very fussy fast though.  The doctor did put her on Zantac two weeks ago to try to help her belly and her spitting up. She now rarely ever spits up but when she was, she was spitting up a large amount.  She does sneeze often, has hiccups often, and coughs occasionally.  She has been rubbing her eyes and nose frequently. I'm sure she's tired but I feel she's been doing it a lot more than she ever has. 

Many advice would be great. I'm willing to do what I have to!