Hey there,
It sounds like you're running into an issue when trying to send photos via Messages, correct? We'd like to help.
Just to confirm, are you using these steps to try and send photos from Messages? Send photos on your iPhone or iPad with Messages
Does the issue only happen when you try to send a photo in Messages? Are you able to send and receive other messages without an issue?
If you're experiencing issues sending or receiving messages, this page has some information and steps that can help: If you can't send or receive messages on your iPhone, iPad, or iPod touch
You mentioned that iMessage is enabled; did you check by going to Settings > Messages > iMessage? Also, under Settings > Messages, is MMS Messaging enabled? More about SMS/MMS here: About iMessage and SMS/MMS
Thanks!