22lbs in 4 weeks is a fantastic loss and you should be very proud
There could be any number of reasons why you had a slower last week, totm, water retention etc but I'm sure that will increase again at your next weigh in
On average this diet loss is 14lbs a month - you are already ahead of this. Try to look at the overall loss per month rather than weekly.
1 st 8lbs is gone forever - please don't be disappointed.
Keep up the hard work and good luck for next week (AAM?)