Our skin covers most of our body. The presence of many diseases inside the body can be understood by looking at the skin. Various skin changes such as discoloration , boils, etc. can be a sign of a big disease. If you notice these symptoms , especially if the symptoms last for more than a few weeks, be sure to contact a doctor. Rash and rashes on the skin - rashes that cannot be treated with medication , and are accompanied by symptoms such as fever , joint pain and muscle aches , may be a sign of an internal problem or infection. - If you have an allergy to something or if there is a side effect of any medicine, it can also be a symptom of rash. - If you have a darker rash than the skin on the back of the neck, it may be a sign of type 2 diabetes. In rare cases, it may be a sign of stomach or liver cancer. - Reddish rash on the underside of the feet that does not go away with common medicine - This may be a sign of Hepatitis C infection. Skin discoloration - In case of diabetic patients, when the skin color becomes tan, it should be understood that there is a problem in the iron metabolism of their body. - Yellowing of the skin may be a sign of liver disease. This yellowish tinge can also be seen in the white part of the eye. - If the skin color of elbows , knees or various old wounds becomes darker than before, it may be a sign of a hormonal disease , such as Addison's disease. Boils , blisters or lumps - these are the symptoms that can lead to cancer , so be careful. - Sometimes it can be a symptom of a hereditary disease. - Yellow lumps in different parts of the body can be a sign of diabetes. - Even what looks like acne can be a sign of another disease. If a woman has acne along her jaw, it may be a sign of polycystic ovary syndrome. Along with this there may be all the symptoms like weight loss , hair loss.