Find out what's running processes on our website that is causing it to overload

Our website has been working fine for almost 2 years. We use wordpress to build the site. Purchased a theme, have a few plugins (the common ones) and it has always been fine. [login to view URL] had a good speed But [login to view URL] was very very slow. So we contacted the theme support, created a login on wordpress for them so they could have a look 1st day afternoon, they logged in, it was fine 1st day evening, I logged in using my own username, updated a few blog posts, it was still fine 2nd day morning, the site had database connection error for both [login to view URL] and [login to view URL] We contacted our hosting provider. They said there were a lot of processes running in the background, leading to an overload problem. They killed the processes, our website worked for a while. In the past 3 days, it worked for a while, then stopped working, then worked for a while. Since they said it had something to deal with the script, this morning we bought a new theme from a completely different company. We removed the theme support's login. We had also deleted all the plugins. And installed completely different new plugins. This afternoon we still had the same problem. We contacted our hosting provider again. They still said there were a lot of processes running in the background, leading to an overload problem. We want to find out what the processes are so we can remove them. We have a long list from our hosting provider showing us the processes. Something like this - 10291 24.1 1.2 162908 49636 ? S 11:25 1:38 /usr/bin/php 10292 1.9 0.4 130564 16372 ? S 11:25 0:08 /usr/bin/php 10293 1.7 1.0 154948 40508 ? S 11:25 0:06 /usr/bin/php --- Please list - what you think you will do - what other information/ logins you will need. - how long it is going to take for you to find out what the processes are