Bless you, . Wish I could give you a big (but gentle!) hug! I ended up in tears after being prescribed medication too. It is a LOT to take in. I am really sorry to hear that your rheumatologist was not forthcoming with information or addressing your concerns. I hope you'll get an opportunity to discuss your concerns with either your current or a new rheumatologist, and ask any questions that you need to. Will you let us know how you get on with getting a second opinion?
Unfortunately all medications have potential side effects, but that doesn't mean that you will get any/all of them. We're all so very different. I am taking methotrexate and so far I personally have just had mild nausea, but I know others have had quite a rough time with it. It would be great if there was a way to know how you'd respond/react to a medication before taking it ! Feel free to browse the forums/Q&A section for different experiences on this.
With regards to prescribing both the biologic and the methotrexate together, my understanding is that methotrexate can increase the effectiveness of some biologics, and it can also help prevent the body from developing antibodies to the biologic. When more than one treatment is used at the same time, this is called "combination therapy". We have a little information on this within this article: https://psoriatic-arthritis.com/treatment/
I hope that this is of some help. We're here for you! How are you feeling today? <3
-Catherine, Community Moderator