Setback?

I'm learning that recuperation from surgery is never predictable and smooth.  Yesterday I experienced a day of severe pain which caused me to take the maximum dosage of my pain killer medication.  I have no idea what caused this sudden reversal to severe pain, which brought me to tears, but it seems that the worst of it is over. 
It started in the morning, and I was unable to complete my usual daily chore of watering the potted plants on the deck with the hose, a very easy thing to do.  Besides giving the plants the water they need in these high temperatures, it gives me time outside before the heat drives me inside and allows me visual contact with my flowers to make sure all is well.  But I had to quit yesterday morning and take 2 pills instead of 1, which lowered my pain to a manageable level.  In fact, when the time to take my medication again rolled around, I opted to take only 1 rather than 2 because I wasn't in that much pain.  Big mistake!  Three hours later, right after dinner, the pain came roaring back, making moving impossible without moaning and groaning.  Sitting didn't help; standing didn't help; laying down didn't help -- and I started shivering with cold.  My husband, Bob, kept checking on me while he worked outside, setting sod in the ground so it could start growing.  Eventually, I wandered outside, desperate to get warm, and sat with a blanket around me in 85 degree heat, and it did help me warm up.  I then returned inside and called the 24/7 phone number that was given to me in case of complications.  A few minutes later, the physician on duty returned my call and had me take my temperature -- 99.5.  I was instructed to take 2 ibuprofen with my pain medication and to apply ice to my back to get through the night and to call my doctor in the morning.  Remarkably, the ice and ibuprofen helped me sleep soundly.  I took my pain medication at 4 AM, my usual time, and woke up at 7:30 AM.  Getting out of bed was uncomfortable but not painful.
I called my doctor, who was in the Operating Room at the time, after taking my temperature (97.00 -- really) and have been given instructions by another physician to take Tylenol or Motrin with my pain medication and to periodically continue ice applications.  My doctor will be consulted this afternoon, and I will then be called again.
With my pain level now again under control, albeit with twice the medication, I'm able to function, but my back and hips ache horribly.  Bob looked at my bandage (3.5 inches long) and can't see any redness or swelling around the area, so infection doesn't seem to be responsible, but I would like to know what's causing this sudden setback and acceleration of pain.  Needless to say, I'll be taking it easier (is that possible?), even though I'm tired of sitting!  I've almost completed the blanket I'm making for one grandson and will probably finish it today, but I'm wondering what will then occupy my hands and time.  If I could pull weeds and take care of my gardens, I'd have plenty to do, but such isn't the case!
It looks like we'll get some much-needed rain today; I've been watching the radar on my computer, but I won't hold my breath.  We've had rain come as close as 2 miles and not hit us, so I'm not going to get excited about the showers building to the west; I've been disappointed too many times.  But the wind is picking up and the clouds are rolling in, so maybe . . .
I'm going to close here and sit outside for a few minutes and listen to the birds sing.