In your opinion, is it a milk intolerance? Do you think his congestion is due to milk?

Hello! My baby is 6 weeks old. From the time he was born until two weeks old, I was almost exclusively breastfeeding. I filled with Enfamil formula already prepared (2 to 3 feeds a day out of a maximum of 7-8/day). From the 3rd week on, I gave more and more formula milk and now only that (Enfamil soft powder for the tummy). Baby has had a consistently stuffy nose since week 2. At first there was mucus when I was doing the baby fly and hydrasens. Since two weeks, nothing comes out in the baby fly but he is still as congested. At night it's terrible... I raised his mattress, I put a humidifier and I do the hydrasens at each diaper... but he's miserable. I saw my doctor and she suggested I give him water after he drinks. It does absolutely nothing. Also, when he is awake, he never stays in a good mood for long. He gets sick to his stomach quickly...he stiffens up and cries a lot.