Well, from what you said, I can see that you might have been a little bit tired recently, and made bad use of your eyes, so that eye strain let it happen. For painful eyes is an indication of your eye health problems. Anyway, to fix eye strain, you must make sure of good rest and proper use of your eyes. Just pay more attention to your eyes, and take breaks from time to time.
Yes, you should reduce the times that you use your phone. Your eyes may get infection or the tiredness because of long time use of eyes in front of computers or phones. You need to use some eye drops with anti-inflammation to moisture the eyes and let eyes get comfortable. At the same time, you need to have the good rest for the eyes.
Well, from your description, it may be because of overuse of phone. So you should just reduce the time you watch phone. Generally speaking, in daily life, many people read phone all the time. And maybe it is just your case. And if you read the phone for a long time, and do not have any rest, it will just make your eyes be stressed. And in that way, your eyes will get eye strain. In a long term, of course, it will damage your eyes, leading to some eye problems. For example, your eyes will be hurt, and painful. And then, if you still do not be aware of this, it will lead to more serious problems. So just be careful about it.