Tooth hurts when dentist hits it.no infection seen on xray.dentist says we should wait to see how things develop but i am so afraid. what should i do?

Tooth pain: Signs of tooth infection are often not initially visible on an x-ray, and take time to become evident. Soreness may be due to infection, fracture, grinding or clenching, malocclusion, gum disease, etc. your Dentist has suggested a very normal conservative option. If you are concerned, seek opinion from a tooth pain specialist, an Endodontist.

Read below: Can be a multitude of issues or nothing at all. Need more information to determine. If an upper tooth, can be sinus related, such as sinus infection or allergies, can be a subliminal fracture or periodontal involvement. Speak to your dentist or find another practitioner if your needs are not being met.

Seek endodontist: Does the tooth have a large filling? Has it been traumatized? Radiographs don't always show the big picture... there can be a non-vital tooth without an "abscess". Did your dentist check to see if the nerve in the tooth was alive or not? Why wait until you are in unbearable pain? Seek a second opinion now.