The results helped him to maintain fifth place in the Showdown, but edge nearer to the riders ahead of him.
Starting the first of two races on Sunday from a third row grid position in wet conditions, Hicky started well to hold third place on the first two laps.
He passed Josh Brookes on lap three to take up second place, but then began to drop down the order to fifth. He was struggling with rear tyre grip and as the race went into the final stages he fell back to ninth on lap 12.
But when leader Dan Linfoot suffered a blown engine, the race was ended four laps early with Hickman awarded eighth place.
Hicky began race two from the sixth row and it looked a huge task to get on terms with the leaders.
But the Lincolnshire rider was fired up and was quick out the blocks, making up three places to 11th on the first lap.
He was soon up to eighth and followed Shane Byrne for a few laps before Josh Brookes caught and passed him on lap nine.
Latched on to the back of a four-way battle for fifth place, Hickman soon dispatched James Ellison and Christian Iddon to take seventh, and on lap 15 he passed Byrne.
One lap later he passed Jake Dixon and reeled in Brookes, passing him at Hall Bends on the final lap to secure fourth place and pick up a further 13 championship points.
Hicky said: “We had an average race one which put me such a long way back on the grid, 14th for the second race.
“When conditions are like that it’s hard to pass, but I was a bit of a bully at the start and got my big elbows out and beat Shakey into the chicane on the first lap.
“It didn’t quite go right for me but I made some good places up before getting stuck behind Brookes and Shakey a bit too long later in the race and made a mistake trying to pass Laverty and let them both back through.
“But I felt so fast, nearly a second-a-lap faster than the leaders on the last couple of laps.
“If I could have got through a couple of laps earlier who knows what would have happened.
“The championship is still wide open and it was only Leon Haslam that pulled points on me in that race so although I am falling a bit behind to him I am gaining on everyone else so the championship is still wide open.”
Hickman has 530 points with two rounds and four races left. The next round is at Assen, in the Netherlands, on October 1.