A recent entry on our Forum states that the writer's doctor has given up on him after seven months of sneezing and treatment for hayfever and asks whether anyone can help.  This is a question we are asked on a daily basis - symptoms may change but allergy sufferers are looking for an answer and possibly a magic solution to their symptoms. Sadly we are not in a position to give a blanket solution since it simply wouldn't work. We can give you pointers and the results of many years of personal experience and supply you with safe products but the detective work can only really be carried out by you.
Everyone is different and allergy triggers can be as varied and surprising as the people they affect. An ecological doctor in Canada was the first person to ask me whether there was any pattern to my or our children's symptoms. I looked carefully at my week and when the real lows were and a pattern immediately showed up - this was the simple bit for us in diagnosing multiple chemical sensitivity. At the time my husband and I owned and ran a pine furniture making business using chemical finishes and it was on the days after I had been there that I could barely lift my arms up and felt very depressed.
For most symptoms the pattern is not as obvious because symptoms are often ongoing and there may be no relief from them. However, it is a good idea to keep a diary of:
How you feel
Where you are
What you are doing
What the weather is like
What you eat
What you are wearing
Your symptoms
Sometimes one's symptoms improve and then suddenly return with a vengeance and unless you have documented these various aspects of your life it can be very difficult to know what could be causing the relapse. It may be some time before a pattern shows up and it's always important to remember that your symptoms may come on as a result of overload.  When I think of overload I imagine my body as a ship in the water with various containers aboard that reflect the foods and products that I use on a regular basis and can cope with. The ship may be a bit low in the water but is stable until a few more containers are added - perhaps foods that one is less tolerant of, perfumed detergents, a new carpet in the house, moulds. The boat (or body) becomes overloaded and can no longer cope which is when the symptoms become much worse. By removing a few of the containers one's body is able to cope again.  This can be why if you are away on  holiday you can tolerate things that you cannot tolerate at home remembering that one of the containers could be stress which undermines the immune system and makes the body more vulnerable to triggers of various kinds. 
Going back to the person whose doctor has given up on him - sometimes one can start to react to substances that previously have been tolerated and this could also be the result of overload . Often the introduction of a new piece of furniture - a chair, a sofa or a new mattress can be the catalyst.
Approach the situation like a detective and look at everything (even things that have not changed) and if you need help please give us a call.