You could go to foodallergy.org or medicinenet.com to find information online. However, the best way to find out about food allergies is to consult a doctor.
Two specific websites that have areas that focus on that are www.foodalergy.org and www.webmd.com. Each of those have areas that talk about food allergies, the symptoms, and treatments.
There are numerous websites online that can give you information on dust and mold allergies. One such site to find this information is on http://www.indoorclimatesolutions.net/
There are many sights on allergies caused by pollen on the websites. Go to Google and type in pollen allergies, but be sure that the information you get is reputable. Mayo Clinic is the best.
Information on dust mite and other allergies can be found on WebMD. Symptoms, and treatments of dust mite and other allergies can be found. The Asthma and Allergy Foundation of America has information on their site as well which one may find informative and useful.
You can find information on nasal allergies online at http://www.medicinenet.com/nasal_allergy_medications/article.htm. You can also visit a doctor for more information, and even medication that may help ease your suffering.
One can find symptoms about panic attack symptoms on MD Online or MD Doctor Online or Healthcare online or at their local hospital or family physician.
You can find information on depression symptoms from your family doctor or from online sites or forums. You can also find information in health books or magazines.
One can find information about ulcerative colitis symptoms on a online medical database such as WebMd, MayoClinic, or the NHS (National Health Service).
Here's some information about it from the Mayo Clinic: http://www.mayoclinic.com/health/peanut
There are numerous resources to find information on the symptoms for HIV and AIDS. The WebMD online information is very accurate. One can also refer to the local library to find detailed information on symptoms for HIV and AIDS.
Information about IBS symptoms can be found online from sites such as Web MD and the Mayo Clinic. There are also specialist sites such as About IBS which can provide information.