Why are my text messages being so problematic (S5)?

[JAKES5]

S5 text issues!

hi;
new to the forum looking for answers...
I have a 8 month old S5.
lately when sending texts... if I press send and then close screen before it sends (ie while the loading circle is still going....) it fails. normally if I wait in that screen it goes through. message comes up grey and I have to resend it.
it may be in my mild but it also seems laggy.
no other issues.

so far I have

turned on and off
removed battery and left and tried again.
removed and cleaned sim card.
done a soft reset (clear cashe data).
issue persists.
happens everywhere even with solid signal.

thanks in advance!