At night time or sometimes i finish taking a shower or sometimes when i swet and start colling, my waste or thy starts iching. and at night sometimes my thy and below armpits gets ichy is this allergies?

Could be a combination of allergies plus both sensitive and dry skin; could also be many other things.

If the problem is dry skin, try applying a hypoallergenic lotion immediately after getting out of the shower. You might also consider using a milder soap. Some soaps are detergent-based which means that they remove almost all of the oils from your skin, including the protective and nourishing oils that prevent excessive dryness. When your skin is excessively dry, it cracks which usually feels like a combination of itchiness and burning. Dry, cracked skin is unhealthy because it allows bacteria, viruses and fungus to enter into the blood.

If your problem is allergies, either get an allergy test or experiment yourself by using only one product at a time for about a week. If you notice your condition staying the same or worsening, then you may be allergic to this product. This experiment is difficult to do properly because most people use several products at the same time. You should also test whether you are sensitive or allergic to laundry detergents, fabric softeners and dry cleaning solvents.

Medicines including the over-the-counter drugs and foods can also cause skin sensitivy or allergies; for example, the antibiotic minocin makes the skin more sensitive to sunlight [sunburn] and also causes itchiness.

Poor nutrition esp. vitamin and essential fatty acid deficiencies can cause skin dryness.

There are still other possibilities. Overweight people often find that their sweat accumulates in skin folds such as their arm pits, groin and other parts of the body that don't get enough air circulation [usually wherever their clothing is tighest]. When sweat accumulates, it irritates the skin. The same thing can happen to people who are not overweight but who sweat a lot. Most synthetic fabrics prevent sweat from evaporating; natural fibers [cotton and wool] 'breathe'.

There are also medical conditions that can affect your skin.

The itching could be due to fragrances in the cleaners you use on your clothes, bedding, and home. Try going all fragrance free with the following products, no air fresheners(they all have toxic fragrances), sprays with scents, scented candles, hair sprays, perfumes, shampoo's, deodorants, fabric softeners, laundry soaps, cosmetics, etc. Note_Beware of products that say "Fragrance free" yet have "Masking Fragrance" listed in the ingredients. The masking fragrance is much more toxic then the original scent is was used to mask. I hope this helps. God be with you.