Puzzling quad pain

hi, after much googling eventually found this site. hope someone can help me understand what's wrong.
up until around 6 months ago my main regular exercise was playing 5-a-side football each week, with no adverse reaction worthy of mention.
in an attempt to get more exercise i bought a bike and started cycling to & from work each day, approx 13 miles in each direction, not particularly hilly.
although i continued to cycle to & from work, work commitments ended up with me stopping my 5-a-side until around 6 weeks ago when i had my first game back for a couple of months.
after about 5 mins of the footy i had excruciating pain in my quads,one leg slightly less painful than the other, but both unbearable.
i had to leave the game and remain stationary for around half an hour, trying to gently rub / stretch to ease the pain (i had no idea what was wrong / what to do), before i could eventually start to gingerly walk around.
it seemed so bad i expected to be in agony the next few days, but by the morning after i think (i cant remember for sure) there was hardly any sign of anything having been wrong the evening before.

i thought this was just a one off, but this week i had another game, the first since the problem, and i had a repeat, although less severe. this time i managed to last the game, but mainly by not running much at all.
this time i have slight stiffness in my quads the day after, but i cant help thinking that my cycling must have done something to my muscles that makes them now not want to run at all.

anyone able to take a guess at what's wrong & what i should do to fix it, whilst still being able to cycle to/from work each/most days ?

many thanks.