Methotrexate and colds

I have been on low dose methotrexate for 5 or so years. Initially 22.mg pr week (one dose), then 17.5mg and now 12.5mg. I have minor psoriasis on one elbow and upper arm so the medication seems to have the psoriasis in a fine balance. My psoriasis is very likely stress related (physical and emotional) and I fully expect that in 4 years when I retire I will aim to stop the methotrexate. Over the last 5 years my health has been good, diet is well balanced, exercise and fitness is good and alcohol consumption minimal. I have seen very little evidence of any impact on my immune system and typically would get a cold once a year. However since September 2018 I have had three humdingers of head colds and coughs. I am not sure that this may just be because I have been closely exposed to friends and family with the cold or if the methotrexate (at that dosage) would have an effect. I am seeing the skin specialist in a couple of weeks for my annual check up so will ask then. Anyone else got thoughts or experience?