Random chunks of post disappearing. Can't publish.

I’m trying to write a blog post but every time I do anything (eg save a draft, preview it, insert a photo), something will go wrong, usually a large chunk of text and a photo or two disappearing, but sometimes chunks of text being duplicated in other parts of the post or links vanishing. The post is about 600 words long with about 5 photos, so not excessively large. Also, it won’t let me publish.

Also, WordPress keeps claiming that I’ve timed out and demanding that I log in again about every five minutes.

I’ve no idea why this is happening. The only thing I’ve changed lately is to update to the latest version of Akismet this morning. (I’ve no idea how to revert to the previous version, so can’t try that.)

I also can’t upload photos today, but that’s a common problem here due to rubbish internet connection, so I’m not stressing about that quite yet.

Any advice please? I’m a VERY basic user, so please don’t assume that I know how to do anything. Thank you…