Does anyone have any information on lactose intolerance?

I suspect my son may be lactose intolerant. Could anyone give me as much info as possible on the subject please, foods to avoid other than the obvious, and possible alternatives. Is there anything I may have done to cause this, I know that may sound daft but as a mother you worry about these things. He has always drank large quantities of milk from being born and it has never affected him before. He loves yoghurts and cheese, and has always eaten lots of them. He is 3 years 10 months, why would it show up now instead of from birth.
The symptoms started after a bad case of diaoreah, at first I thought it was linked, but it has gone on for weeks now. The symptoms match up exactly to lactose intolerance, also I tried to avoid dairy products and after about 3 days there was an improvement, then I gave him a yoghurt and the next day it was bad again. The doctors have treated him for a parasite infection but it has made no difference so I don麓t think it was that.

When he had his bad tummy initially, it can take a long time for everything to go back to normal. Avoiding dairy is the best thing to do with any upset tummy, it may be that he is still a little tender in his tum, and he has also has treatment for an infection, this will have upset the balance in there as well.

Lactose intolerance is caused by the inability of the digestive system to break down lactose into glucose. The enzyme which breaks down lactose into glucose is called lactase. The lack of lactase can be caused by tummy bugs and digestive problems which your son has had, so it may be as I said, that its just a temporary thing while his tummy settles back to normal - its a delicate balance in there!

The only thing to do it to go back to the doctor, and explain your fears. There are a few ways he can diagnose it, either a series of blood tests after fasting, a hydrogen breath test, or a stool acidity test. Or he may suggest a diet change under his supervision.

Dont try and treat him yourself, your doctor can get things sorted much quicker for you, in the meantime, go to www.lactose.co.uk and have a read, see if the other symptoms match what it says on the site.

You shoudl see a doctor fisrt.

Drink Lactaid milk. Try to avoid things like ice cream, milk shakes. Im lactose intolerant. Its no big deal. Certain things just make you crap really bad.

try nhs direct, that should give you all the info you need

I agree with lozzielaw entirely. She knows her stuff, and as a fellow lactose intolerant I can agree. I diagnosed myself, and put myself on an exclusion diet, BUT when I was an adult. You son needs to be referred to a dietitian, through your GP.
Just remember, any exclusion diet will make the condition seem worse before it gets better. The body has to get rid of all the 'toxins' build up in there before it can improve. I was told 3months total dairy free would clear it all out, then improvement would show.
DO NOT DO THIS WITHOUT MEDICAL SUPERVISION.
Go to your GP and ask to be referred.
It may also help if the family can embrace the same, or similar diet to 'include' your son, rather than 'exclude' him, from certain meals. The most depressing thing for me was sharing the meal time with my husband who was still eating pizza, cheese on taost etc, while I experimented with dairy-free (sometimes awful) meals.
I wish you, and your family well.