One of my wordpress sites is taking forever to load and won't load in some cases

One of my wordpress sites: http://relievestressstopanxiety.com/ is taking forever to load. Sometimes the site itself, but worse is the wordpress admin area. In some cases I can’t fully load a photo into a post, I can’t load a plugin page, etc. My other wordpress site is working fine. I’ve been having this problem for days now and it is driving me batty–and this my work site so it is important that I get it resolved.

Can anyone give me any help? I am completely stumped.

Thank you in advance.