Whats wrong with my plants? Mosaik Virus?

Hi, i bought 3 tomato plants from an old woman and put them in 10l pots. They have grown really well and have grown quickly, they have not been fertilized (only a little kelp after repotting) and have not been overwatered, etc. They are in partial shade under a roof, so no rain. Temperatures are 45F(8C) at night and 70F(20C) during the day, three days ago it was 41(5C) at night. I noticed the spots on the leaves 2-3 days ago. What could it be? Do they possibly have the mosaic virus or were they just too cold at night? I am grateful for any help and hope it is not a virus. If so, I would have a heavy heart and dispose them straight away as I have other plants on the balcony and don't want to put them at risk of being infected too. Thanks in advance!