Sorry to hear you've been running into problems. DigitalOcean droplets are self-managed, and there are many things that can lead to a process on your droplet crashing. If you open a support ticket, the team can help you find the root cause.
On common issue is MySql running out of memory on smaller droplets. You can check to see if that is where your problem is coming from by examining your logs. The following commands could provide you with some insight:
grep -i "out of memory\|oom" /var/log/dmesg
grep -i "cannot allocate memory\|can't allocate" /var/log/mysql*/error.log