Based on everything below, I have nothing to add about getting your supply back up. (BTW, fenugreek only works if your supply is low because of certain factors. I took it, smelled like maple syrup for 3 weeks, and got no benefit from it)
As far as formula type, if your baby has issues with dairy (as many do, my Pediatrician told me it is the #1 cause of GI distress in babies), the first formula to try is soy. If soy formula doesn't work well, then there are a myriad of other options out there. I would start with soy then consult your Dr if that causes problems.
Good luck. Try not to freak out too much (stress will cause issues with your supply) as you are clearly going through a hormone shift with the spotting. Avoid caffeine, get lots of water (try drinking a beer while nursing--lots of fluid, nutrients, relaxation benefit, and alcohol doesn't go straight to breast milk. My Dr told me this one, but I HATE the taste of beer, so no go for me). You can also try Mother's Milk Tea...