ALIMENTUM baby has gas, major spit ups, colic and fussy - tried enfamil ar, now on isomil but less improvement

She was on Enfamil plain till she started spitting up and getting gy so we switched her to Enfamil A.R. but found blood on her stool indicative of milk allergy. Now she's on Isomil for 1.5 wks but noticed less improvement. We would burp her for an hr after feedings but still gets gas so we give her simethicone and gripe H2O almost everyday. During naps, she doesn't sleep well but squirms as if trying to p gas and episodes on some days where she just screams and you can't tell what's wrong with her --- thinking of switching her to SIMILAC ALIMENTUM as a last resort... Anyone been on the same situation as mine and had to give baby Alimentum .. would appreciate help -- serious answers only pls?