Mingo, the cat that hates his parents

This is my story... I have always been a cat lover since I was a child. When I got married a friend on mine found Lolo, a lovely kitten lost in the middle of the mountain, at least two miles away from civilization. He was biking with his dog and Lolo followed him a long way and stayed outside his house two days waiting to be adopted, so my husband and I decided to take him home. Lolo is the most social and loving cat I've ever met. We decided that Lolo needed companion because he was all day alone. We went to the local shelter and adopted Mingo, a two month's old kitten. Lolo at first hissed and complained about Mingo's presence, but after two days they fell in love with each other. Mingo started having health problems because of some stomach parasites with were strongly contagious for human beings. Both Lolo and Mingo were sick, but Lolo, a big healthy cat healed very fast, Mingo's treatment lasted around one month, and was kind of traumatic for him. After this, Mingo hates us. Mingo is one year old and he never lets us pet him, he is agressive with us, if we try to pet him he will hiss and bite. I feel very sorry because Mingo is not a happy cat, and the strangest thing is that he is so loving with Lolo, he just hates his parents and he is highly stressed all the time. I am really lost, I don't know how to help Mingo, nothing like this has never happened to me. Help me please!