With a 5x5 program you need to pick a weight that you can dominate for the 5 sets of 5.
Further, most 5x5 programs ramp up, meaning you start lighter on the first set and add weight until the last set or two is challenging. (3x5 is usually straight sets though)
So in light of the first two recommendations, reduce the weight by a significant amount.
The fact that you were really sore 4 days later and couldn't even handle the same amount seems to indicate that you simply did too much too soon that your body wasn't ready for based on your previous routine.
Ease into the 5x5 routine, it may be frustrating, but for a few weeks go really light but train often. Maybe even every day, but using 50% of what you attempted. So instead of 185, go with 90 or 95. Then gradually work up the weight and of course, make sure you are eating and sleeping enough.
If you reduce the weight and ease into it, I believe you can experience a long period of steady linear progression and you will be quite happy with the results.
James 1:16-17 ESV
Do not be deceived, my beloved brothers. Every good gift and every perfect gift is from above, coming down from the Father of lights
With God's help...Mens sana in corpore sano