I can speak from my experience and that of one of my friends as we are both going through this right now (both of us in and out of the hospital for small bowel obstructions).
For me, my first sign was VERY loud stomach grumbles that may or may not be associated with pain, usually mild. Next, I would notice that I have stopped using the bathroom, and then the pain would get worse over a few days (as the sounds got louder). I would usually feel the pain in the "center" of my body right at the base of my rib cage even though my 15cm stricture was in my terminal ileum. The pain would come in waves and be relieved by the loud grumbles. For some reason, the pain was no better or worse when I ate and I only vomited once the first time completely voluntarily (trigger) because I didn't know it was an obstruction and thought if I threw up it would relieve the pain.
Now my friend. He has had three blockages in the past few months and he feels it a bit differently. He said first comes pain, then a lack of appetite, and then severe vomiting (8 times in 2 hours).
I have been VERY VERY paranoid since my recent incidents and think that everything is a sign of obstruction only to find out a week later that I am still ok. One thing I can tell you for sure is that at SOME point there will pain and at that point, unfortunately, you need to worry. Some people can wait it out and the obstruction will clear, but sometimes you need to go to the hospital. If you don't go to the hospital and be monitored, there is a chance you can perforate and then it only gets worse from there...
I am not advocating NOT going to the hospital but since you just started Remicade it could just be taking time for meds to work. If you do wind up having an inflammation-caused blockage (as opposed to scar tissue) and the Remicade starts working, it should "open" you back up again.
Any questions feel free to reach out.