Confusion about lip trill

So am I supposed to do lip trill slide in chest voice on the lower notes because it hurts my throat when i do it thay way. If I do chest to head voice on lower notes in the slide it feels a lot better. Idk if that's correct tho. It's easier for me to do lip trills in head voice but whenever I try it in chest my voice tends to get sore and I run out breath or the lip trill just stops abruptly is there any way to help this thank you.

Please let your voice transition into mix or head voice when it wants to (on the lip trill)! It also helps to imagine you're singing an UH vowel (as in BUG) all throughout. 

I can't lip trill too well In chest voice.  Sometimes it works but most of the time when i try it either hurts when I go up or   my lips stop. Is there any reason why this would cause a little discomfort?? I can do it head voice tho. During the lip trill slide I can do the first note of the lip trill in chest voice but the higher note that we slide to I can't do unless i push or just do it in head voice Instead. Is it fine if I do it this. From chest to head voice? Sorry I was a little confused to what you responded to me. Is it normal to not be able to lip trill in chest voice should I just not do them what other exercises can i do to strengthen my chest voice. 

The lip trill isn't comfortable for everyone! I recommend trying other semi-closed exercises like the NG or straw singing instead: https://www.voicescienceworks.org/sovt-exercises.html. 

Here's a quick lesson on chest voice: https://www.youtube.com/watch?v=sc8UWXwEGuQ

And here's a chest voice series for you: https://www.30daysinger.com/tutorial/daily-chest-voice-workout-for-beginning-tenors-and-high-baritone/1

Enjoy!