15 week olds and cow milk

So i have had a problem producing milk and my son has been on similac advance since he about 2 weeks.3 weeks ago he reduced his eating and did not want to drink his formula.He would act hungry but cry if he was given formula.His cardiologist had advised us to give him an ounce of water whenever he showed signs of having problems passing stool.So every time i gave him the water he would drink it so fast,but the minute i do a quick switch to formula he would cry.Having a baby with heart problems and potentially needing surgery in the near future weight gain is a real concern,feeding is also a concern because we always have to look out for any stress on his part while feeding.
So this weekend i had my relatives over for a visit.One of my uncles a doctor evaluated him and the contents of the formula and thought it best he be switched to organic cows milk.So we did that while he was still here so that he would notice any potential side effects.By the way if you are thinking he is one of those old time doctors who prescribes to unconventional methods ..he is not.He is a well known doctor,i will however leave out his identity because i have not asked for his permission to include his name on my blog.
Well anyway my son started taking the Natures promise organic milk last night around 12am,mixed with one part water,By morning he was fine happy was not fussy was taking his milk eagerly,so we excluded the water since morning and the difference is like night and day,he has taken about 20 ounces of milk today by eight when he had last week decreased to less than 10ounces a day.He is pooping better than he was,a better consistency and not as much straining.. he is so energetic and for the first time in months did not cry up a storm today.He cries alot,everyday like clock work from 2pm to 6pm he will cry his little heart out.His doctor said he had colic so i should try gripe water and mylicon or little tummies gas drops,unfortunately he would throw up every time i gave it to him i tried giving it to him slower a tiny drop every five minute but 15 or so minutes after the last drop he would throw up everything.
So as the very caring mother to this little boy i chose to take my uncles advice natures promise organic milk and formula only 2 times a week just for the vitamins and such.
Before anyone decided to try this out though i advice you think it through and talk to a doctor you trust.I know most doctors will tell you the over sung tune formula or breast milk until six months of age,I agree that breast milk is best and i still continue with the domepridone and pumping whatever i get i give to him but until i have breast milk he is on cow milk.Its a mothers intuition here over formula marketing.