A hard decision to make

I share some of your issues and I, too, struggle to keep working.  I thought I might have to go the disability route last year, but I tried some other drugs and improved enough to keep going. I would urge you to try enbrel, or another drug.  Some drugs work better than others for different reasons and different periods of time.  If it doesn't get better for you, then consider a 2-3 week break from work.  When things get really bad, a long rest sometimes works.  Blessings!

Ordinarily, I'd recommend that you explore accommodation options with a new job that may make it easier for you physically - for more on this and links to resources, check out my post on Working with RA. However, if getting dressed as a job, you need to address your condition(s) before you can make your job easier. As someone else recommended, talk to your rheumatologist about treatment options like e.g., the Biologics - they have been miracle drugs for many people, making a significant difference in their ability to live their lives. Personally, I'm on Humira and it has gotten me from the point where getting dressed was a job to where I have a job - it took me a couple of years to get strong enough to get there, but I did get there and more importantly, even before that, I laughed every day again (check out my post on Better Living Through Chemistry for more on this issue).

Does your employer offer short-term disability with pay? If so, speak to your rheumatologist about how much time they think you need in order to get back on top of things again. I'm the other hand, there comes a time where working becomes counterproductive to living your life. Applying for SSD doesn't mean you're giving in - it means you're facing the reality that you need time to deal with your illness and that work is actually making you worse, thereby making it more difficult for you to treat your body with the kindness it deserves. Unfortunately, getting SSD can be a royal pain - a while ago, I wrote a post on applying for SSD and it has links to resources that can help you reduce the risk of getting denied on the first go around. Once you're on SSD, you can work part time - it's commonly acknowledged that the amount you get isn't quite enough to live on, so you're allowed to make some extra money. Check with at least three people in senior positions about how much that is - the main number for SSD is kind of renowned for not giving out accurate information. It's also possible that if you start feeling better you may qualify for vocational rehabilitation funding which may help you should you wish to go back to school or to find a career that will work around your illness and that you may be able to do part-time.

However, despite all this factual information, I want to again emphasize that you have a lot on your plate right now and it's okay to say that you can't deal with all of it right now. There's only is so much energy ago going around and when you have a lot of pain and a lot of activity from RA, lupus, etc., you have to put the energy where it matters most (to get even more self-referential, check out my post on the spoon theory). Take care of yourself first, then worry about working.