falling blood sugars

Type 1 Diabetic since 1983. In the past 10 days I have reduced my dose of Tujeo twice - 22 to 20 and carb counting ratio from 1/7.5 breakfast and 1/9 dinner to 1/12 & 1/13. My blood sugars are still falling all the time and within 90 minutes of eating I am having to drink high carb fizzy...