New Monthly Contact Lenses Stinging?

I have a monthly trial of contact lenses which I opened on Sunday. On Sunday there was no pain, except the vision blurred about every minute for about 30 seconds so I couldn t see anything. I wore them four hours. The next day I wore them 6 hours and they were perfect. No problem at all. The next day I put them in and had to remove them after 30 minutes because both eyes were stinging and the water was pouring down. It was more painful than an irritation. My eyes were sore and watery for the next few hours after I d taken them out. Tried them again today and had to remove them quickly because they were painful again. Any idea on what the problem is? The cleaning solution I use is easy vision all purpose preservative free solution (specsavers recommended). Thank you

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