My daughter sees an OT for sensory integration. The best way to describe it is that sometimes the wires get crossed, so touch can make them gag, and so on. The OT does different things to help regulate the childs senses. It works. They will always have this, but you, and later the child, will learn how to work with it, what helps, what makes it worse.
My sister's niece had a problem with sensory integration, and when she was three, they used this special brush on her. They would brush her, and it would calm her down. Eventually, they overcame the problem. She had a hard time touching things, or with people touching her. I have a one year old daughter with spastic quad cp, and we tried brushing her, and it didn't work, she had problems with tone though, not sensory integration, however, her speech therapist's son also had the sensory integration problem and she said that they used the brush on him as well, and it worked. Your child may have problems with GERD, gastro esphageol reflux disorder, that may be triggered by smells as well. Good Luck.
It is not unusual for children to display delays in areas of development alongside sensory integration problems. This is because various areas of neurointegative behavior are closely associated. Occupational therapists diagnose and treat sensory integration disorders. We see many benefits from appropriate intervention, and I don't happen to agree that it is a controversial area. When people display sensory integration problems, and those problems are diagnosed accurately by a qualified occupational therapist, treatment can yield obvious benefits.