Re: HELP! I'm being bullied in the dojo!
One of the things you should be learning from aikido is grace under pressure. This is an opportunity to practice.
If he is being physically abusive, then yes, you absolutely should discuss it with an instructor. At 7 months in, there's plenty that senior students can dish out that you shouldn't be expected to handle.
But verbal nastiness? Meh. Shut up and train.