Liana ~ I have a similar testimony to Alisa, the author of Go Dairy Free.  I was milk allergic as a child and the doctors said I would grow out of it.  I have been eating milk for 40 years. I have always had chronic sinusitis since my early 20's including constant post nasal drip. Most recently I had developed adult acne, fatigue and and joint pain.  I mentioned to a friend how tired I was with the constant post nasal drip; clearing my throat all the time. My friend said that she only got that from food allergies. I later remembered that I was allergic to milk as a newborn and went on a dairy elimination diet the next day. Sure enough--my sinusitis, fatigue, joint pain and acne all cleared up almost within 48 hours!  I have the Go Dairy Free book and it gave me some quick ideas for instantly converting my diet.  The website it great too!