what you are suffering from is "razor itch" this happens due to shaving against the grain of the hair. You must change your shaving habits.
First of all seek help from a dermatologist who will give you required antibiotics and advice.
Next Steps
Instead of shaving, trim the hair using a trimmer or a good pair of scissors. This will suffice. Shaving may also hurt the skin hence nowadays many persons prefer to trim the hair than completely shaving off. It also avoids the itchy feeling felt after shaving for few days. If you must shave, wet the hair for a goof few minutes, Apply a suitable shaving gel to lubricate the hair and heep them manageable. Now identify one area and see the grain of the hair, and shave in that direction. this will remove the hair but prevent disturbing the roots.
Health Tips
After shaving, you must use a body moisturiser to that part to prevent the sharp shaved hairs from irritating the near by skin. Also after shaving wear a loos fitting trouser rather than using tight jeans. If you dont like to use razor, you can use hair removing creams too. But they too can cause skin allergy, so use and see