I agree with Hypo. You will need to get more detailed error information with PHP error log. If "PHP Question2Answer MySQL ..." recorded in the error log, following information will be recorded there.
- Error type
- Error no.
- Error sentense
- Error query (In case of query error)
And, you will need to know about database limit settings (e.g. max_connections, max_allowed_packet, etc, etc). If your server is a shared server, you may not be able to change these settings. However, if your server is VPS or dedicated server, it may be resolved by changing these settings.
Anyway, it is important to explore the cause accurately.