Difficult to start my 99 civic immeidiately after a trip.

I have a 99 civic and recently it develops a starting problem. Normally
the first start of the car is ok. After a trip, it won't start again,
so far I can manage to get it started after waiting some time. When
can't get the car started, on turning the key, the dash lights become
very dim as if the battery is dead. The cranking is kind of slow. I can
hear another kind of clicking noise that comes from somewhere near to
glove box (main relay?). I am also having a "check engine" light on
problem for a while. Every time when I have a starting problem, the
"check engine" light is reset but after I run it one day or two, the
"check engine" light comes back again. I thought the car has a main
relay problem after reading the group, but since it clicks (it clicks
continuously when I keep the key on the ignite position), could it be
something else? I also suspect it is a battery problem ( dim light,
slow cranking), but how come it can get the car started kind of
normally after waiting for some time. So far my car does seem to be
easier to get started when it is cold than warm. It is kind of
confusing.

 

if the battery is original, change it! its due. my 98 civic is starting
to exhibit some symptoms like slower starting than normal. original
battery, too. luckily, i dont rely on the car so i can just let the
battery crap out totally.