1. “Media” is a plural term.
2. The singular is “medium”.
3. “Mediums” should only be used as a term if you’re talking or writing about more than one psychic.
4. “Social media” is a plural term. Think of it in the same bracket as “social tools”, “social platforms” or “social channels” if it helps.
I know we don’t speak Latin anymore. I know that there comes a time when the language inexorably changes and you just have to go with the tide (check out the double possessive rule; if it’s been in operation for centuries, it’s time to give up the fight).
I just can’t help being driven slightly insane by the huge number of articles I read every week entitled “social media is [insert insightful comment / occasional platitude here]”.
I will now go back to being sweetness and light. I’m even planning some baking blogging* for you soon.*While we’re on the subject of unbelievable pedantry… When you mean “I want to write a post about this”, try not to say “I want to write a blog about this”. You’re probably not writing an entire blog about that subject, just one post. I reckon we have probably embraced “to blog” as a verb, though, so you could try “I want to blog about this” as well.