Does it sound like my daughter has a milk allergy?

My little one is 6 weeks old and we are transitioning her to formula from milk. When she was born they had to supplement my colostrum because she was not getting enough and they used Similac Advance. She did ok on that then other than the excessive spitting up. Once my milk came in she fed other than when my mom would let me sleep and she fed her with a bottle. She became very very fussy so we just stopped all together and I started pumping. I noticed when I drank a lot of milk she spit up a lot more of my milk than normal. Now we are trying to find a formula she can tolerate without throwing it all up. We have WIC and they started her on Good Start Gentle. That constipated her horribly, she spit up just about all of her bottle every time so we consulted with her dr and he suggested Enfamil AR. That worked for a few days and then she began the excessive spitting up and of course became constipated from the added rice starch. So a couple days ago my doctor told me to try Similac Sensitive for Fussiness and Gas. It's a milk based formula but lower Lactose I believe and she did well on that for a couple days with no spit up then she started the spitting up again and here I am today wondering what to do. We see her doctor again tomorrow to consult about formula change again. Also, I took her a couple weeks ago because of a rash....she doctor said it was heat rash but she still has it and it's definitely not baby acne. This is all over her chest and back and some on her face and her ears are extremely dry looking so my first thoughts were a milk allergy. Just wanting some opinions so I know what we may be looking at in the next few days. Does it sound like a milk allergy?? I know spitting up is normal, but what she was doing is not normal. Thanks in advance for your opinions!!!!