did you do it after taking a warm bath to soffent your hair folicuals. also waxing is good to profficinal of course

Shaving bumps are often a result of ingrowing hairs. (especially on pubic hair as the hairs are coarsers and curlier) These can appear as tiny little spots, where under the skin the hair has grown inwards and has coiled. These can usually be squeezed out, but should be done gently to avoid scarring.
With shaving or waxing, it is recommended to exfoliate 24-48hrs after treatment. This should be done once to twice a week. This will remove excess skin cells, making it easier for the hair to grow back correctly.
Another cause of shaving bumps is just irritation to the skin. If this seems to be the cause, it can be reduced by ensuring the area is properly protected (with a cream etc) before shaving and that the hairs are soaked and softend first. It can be beneficial to make sure you don't shave directly against the hair growth. This may mean not such a close shave, but will help prevent irritation.

Try shaving each are only once. Otherwise, you will be more prone to bumps. You can also apply tend skin to avoid bumps and ingrown hairs. You can buy tend skin at your local store, such as a Rite Aid, Walgreen's, etc. HTH.